.. index:: angle_style sdk

angle_style sdk command
=======================

Syntax
""""""

.. parsed-literal::

   angle_style sdk

.. parsed-literal::

   angle_style sdk/omp

Examples
""""""""

.. parsed-literal::

   angle_style sdk
   angle_coeff 1 300.0 107.0

Description
"""""""""""

The *sdk* angle style is a combination of the harmonic angle potential,

.. image:: Eqs/angle_harmonic.jpg
   :align: center

where theta0 is the equilibrium value of the angle and K a prefactor,
with the *repulsive* part of the non-bonded *lj/sdk* pair style
between the atoms 1 and 3.  This angle potential is intended for
coarse grained MD simulations with the CMM parametrization using the
:doc:`pair_style lj/sdk <pair_sdk>`.  Relative to the pair_style
*lj/sdk*\ , however, the energy is shifted by *epsilon*\ , to avoid sudden
jumps.  Note that the usual 1/2 factor is included in K.

The following coefficients must be defined for each angle type via the
:doc:`angle_coeff <angle_coeff>` command as in the example above:

* K (energy/radian^2)
* theta0 (degrees)

Theta0 is specified in degrees, but LAMMPS converts it to radians
internally; hence the units of K are in energy/radian^2.
The also required *lj/sdk* parameters will be extracted automatically
from the pair_style.

Restrictions
""""""""""""


This angle style can only be used if LAMMPS was built with the
USER-CG-CMM package.  See the :ref:`Making LAMMPS <start_3>` section for more info on packages.

Related commands
""""""""""""""""

:doc:`angle_coeff <angle_coeff>`, :doc:`angle_style harmonic <angle_harmonic>`, :doc:`pair_style lj/sdk <pair_sdk>`,
:doc:`pair_style lj/sdk/coul/long <pair_sdk>`

**Default:** none


.. _lws: http://lammps.sandia.gov
.. _ld: Manual.html
.. _lc: Section_commands.html#comm